There are known various types of open-end belting which can be spliced, utilizing different means, requiring tooling of varying degrees of sophistication and complexity, and yielding a range of properties of the finished belt.
Thus, elastic belts have been utilized, comprised of various sections made of thermoplastic elastomers and spliced by butt-welding the two open ends together. Such belts are seriously restricted in their pull-foce capabilities and exhibit undesirable creep and stretch. Also, similar belts were proposed with a hollow construction allowing the use of mechanical fasteners and inserts for belt splicing. Thus German Pat. No. P2152215.6 (Woodward) describes a metallic shank to be inserted into both ends of hollow belt for production of an emergency belt. Such joining means are highly unreliable, as the elastomeric material cannot adequately resist shank pull-out. Also, the hollow construction of the elastomeric belt further reduces its resistance to creep and stretch. Additionally, the shank introduces a very stiff section to the belt. In order to alleviate these drawbacks, belts have been proposed where tensile members are embedded within the body element of the belt. Such tensile members could be woven tape of synthetic fibers as in U.S. Pat. No. 4,366,014 (Pollard), or metallic cables as in U.S. Pat. No. 4,283,184 (Berg). In both cases, the body element comprises a thermoplastic elastomer such as polyurethane.
Major attempts were made to provide continuity in the pull capability of the belt in the splice area. Thus in the Berg patent a metallic bushing crimped on both ends of the steel cables is used for splicing. Durability of this type is very limited, however, due to concentration of stresses at the bushing ends.
The Pollard act suggests welding of both belting ends in such a way that the reinforcing tape of both belt ends overlap. This results in a stiff section that shortens belt life and also requires quite elaborate preparation and tooling.
While the method of butt-welding plastic belts appears to be most desirable due to simplicity, quickness and appearance of splice, it was not possible, in the past, to extend the method to longitudinally reinforced belting. Such belting, when butt-welded, breaks at the weld upon flexing due to concentration of stresses at the weld area, as the sections on either side of the weld are stiffer than the weld section. A method circumventing this drawback could provide belts for both power transmission and conveying applications for longer life ratings not possible with nonreinforced plastic belts.